Piano-playing-device expression control



Aprfl 1926.

H. SANDELL PIANO'PLAYING DEVICE EXFRESSION CONTROL obi ihai' l a June 14,. 1922 "4' Sheets-Sheet 1 April 6, 1926. 1,579,793

H. K. SANDELL I PIANO PLAYING DEVICE EXPRESSION CONTROL Origi l Filed June 14, 1922 4 shew-511m 2 llllilillllllllllmii April 6 1926.-

' 4 H. K. SANDELL M PIANO PLAYING DEVICE EXPRESSION CONTROL Original p Jun 14 1922 4 Sheets-Sheet 5 April 6 1926.

H. K. SANDEL-L PIANO PLAYING DEVICE EXPRESSION CONTROL 4 Sheets-Sheet 4 Original Filed June 1922 Bill ism - five/21 071 Patented Apr. 6, 1926.

UNITED STATES PATENT OFFICE;

HENRY K. SANDELL, OF CHICAGO, ILLINOIS, ASSIGNOR T MILLS NOVELTY COM- PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

PIANOPLAYING-D EVI CE EXPRESSION CONTROL.

Original application filed June 14, 1922, Serial No. 568,226. Divided and this application filed April 9,

i 1924.. Serial No. 705,241.

Illinois, have invented a new and useful 1111-- provement 1n Piano-Playing-Device Expression Controls, of whlchthe following 18 a specification.

The present invention relates to unprovements in piano playing devices, and more particularly to such devices operated by means of an electrical current and controlled by perforated note sheets or by manually operated keys, as desired. More particular 1y, the present improvement relates to an expression device control which enables the length of stroke of the hammers in the piano action to be controlled in a very simple and effective manner.

The present application constitutes a division of my pending application Number. 568,226, filed in the United States Patent Otiice on J une 14:, 1922. p

The invention is illustrated in the preferred embodiment thereof in the accom' panying drawings, in which Figure 1 is an elevation of a piano playing device embodying the present invention, the

central portion thereof being broken away; Fig. 2 is an end elevation of thepiano playing action illustrated in Fig. 1', showing in detail the operation of a note-play ng magnet and of the control magnets for the dampers; Fig. 3 shows in detail a sectlonal view through the control magnets for the control of the. hammer-rail; Fig. ishows in plan the control magnets of Fig. 3; Fig. 5

is a sectional view through the action on the line 55 of Fig. 1, showing in detail a noteplaying action and the control magnets tor the operation of the hammer-rail; Fig. 6 1s a sectional view through a note-playing magnet; and Fig. 7 is a diagrammatic view showing the circuits for the control of the various parts of the piano action both from a perforated note sheet and from manually operated keys and pedals.

Referring more particularly to the drawings, the numeral 10 indicates the strmg plate of a piano, which may be, for example, of the character described and shown in my prior Patent No. 1,028,496 granted June 4, 1912. The strings are indicated by numeral 11. The actions for the individual keys are designated by numeral '12 and, as they do not torma part of the present invention, are not described in further detail herein. The action of each key is controlled by a riser 13 acting against the jackbutt Hand actuated by an alternating current noteplaying magnet 15, the construction of which will be further hereinafter described.

The length of stroke of the hammers is controlled by the position of the movable hammer-rail 16 carried by arms 16" mounted on pivots 16' which are supported on the bracket- 16 A spring 16 tends to draw the hammer-rail towards the strings. At one'end of the hammer-rail 16 a pin 17 (F lgs. 1 and 5) projects, this pin being preferably covered with a felt roller 17*. The pin 17 engages one end of the hammerrail operating lever 18, the other end of which is engaged by the felt-covered head 19 of rod 20, operated by the movable core of control magnet 21. By the operation of the controlmagnet 21, the rod 20 is operated either to force the hannner-rail 16 back to its farther-most position to give a full stroke to the hammers 22, or is permitted to assume an intermediate position, correspondingly reducing the stroke of the hammers.

A second magnet 23 co-operates with the magnet 21 and the rod 29 to hold the rod in its extended position. The mode of operation of this co-operating magnet will be clear from Figures 3 and 5, Figure 3 showi-ng the magnets and their co-operating parts in detail. a r

Magnet 21 is torn ed as a coil or spool-2 E of suitably insulated wire, in the center of which is the movable core 25. The coil 24 is formed on a cylinder of suitablenon mag netic material 26. a cylindrical member 27 projects into the opening through the coil, the inner portion of this member being formed to. provide a seat for the end of the core 25, which may suitably be provided with a felt bushing 28 to deaden the sound of impact. A laminated iron frame 29 of generally rectangular form completely surrounds the magnet, undue heating thereof being prevented by its laminated construction. The rod 20 is secured to the end 01 the core and passes through a suitable bore in the member 27 and in the end of the frame 29, a felt bushing 30 being provided to eliminate noise. At the end of the rod 20 the head 19 is mounted, being provided at its end with a At one end of the coilnet 23 is mounted a cylinder 35 of suitable non-magnetic material, for example, brass. A core or armature 36 ismovably mounted within the cylinder 35. At its lower end the core 36 isprovided with a projecting rod portion 37 which passes through a felt bushing 38 in a suitable bore provided in the cap 39 closing the lower end of the cylinder 35. A coil spring 40 in the lower end of the cylinder surrounds the rod-like projection 37 and bears against the end of the core 35, tending to force it upwardly. At its upper end the core 36 is provided with another rod-lilre projection -l1, which passes through a felt bushing 42 in the cylinder and also through a felt bushing e3 in the cap 44: closing the upper end of the c-ylinder 35. At its upper end the projection a1 is provided with a felt head 45 which normally bears against the felt head 32 mounted upon the rod 20 operated by magnet 21.

The co-operation of the two magnets will be readily apparent from a consideration of Figure 5. hen the electro-magnet 21 is momentarily energized by alternating current, the solenoid core 25 is forcibly brought to the center of the magnet and the rod 20 is actuated to push the end of the hamm-en rail operating lever 18. By this movement the felt pad 32 is'brought to such a position as to entirely clear the felt head 45 on the rod operated by electromagnet 23, and the spring 40 in the latter magnet, acting on the end of the core 36, forces the rod ll and the felt head 15 upwards against the rod 20 between the pad 32 and the frame 29. The elements are then in the position shown in Figure 5. Upon tie-energizing the magnet 21, the head 45 then serves as a stop preventing the return of the head 19 of rod 20, and thereby preventing the return of the han'imer-rail operating lever 18 to its normal position. A momentary closure of the circuit energizing the magnet 21 consequently results in placing and holding the rod 20 in energized position, its position being maintained even after the magnet 21 has been deenergized. With the parts in this position, energizing the magnet 23 causes a retraction of the core 36 to the center of the magnet. This draws the head 45 back to a position such as to clear the pad 32 on rod 20 and permit the latter to return to its normal position with the magnet 21 deenergized. By means of this arrangement, for example, if

the magnetsare operated from a perforated music sheet, a single perforation will permit closure of the circuit energiziir the magnet 21 and the parts operated by the magnet will be held in the position after the magnet is (lo-energized until a perforation permit ting closure of the circuit through magnet 23 energizes the latter. The hammer-rail lever 18 is then permitted to return to its normal position under the action of its spring 16 Dampers 46 are lifted from the string to produce the pedaling effect, by the lever 4-7, which is operated by a pair of co-operating magnets 21 and 23 of substantially the same type of construction as electromagnets 21 and 23, and co-operating in substantially the same manner. In these electromagnets, as shown in Figure 2,the various elements are indicated by the same numerals that indicate corresponding elements in the electro magnets 21' and 23 in Figures 3 and 5, the sufiix a'being added to the several numerals. It will be apparent that a morn-en tary energizing of the magnet 21- will operate the lever 47 to lift the dampers 46, and the latter will be retained in the lifted posi tion by co-operation of the magnet 23 until the latter is momentarily energized.

The cores of magnets 21 and 21 are preferably of laminated construction, as shown in Figure 4, undue heating thereof being prevented by this laminated construction.

The construction of the individual noteplaying magnets 15 will be clear from a consideration of Figure 6. Each of these magnets is formed of a spool 48 of suitable insulated wire mounted in a metallic, preferably iron frame 49. Within the spool is a tube or hollow cylinder 50 of non-magnetic material, preferably brass. Slidably mounted within this tube is the magnetic core member 51, provided at its ends with rodhke projections 52'and 53. The rod-like projection 53 passes through a bushing 54 in the cap 55 in the lower end of the tube 50 and serves as a guide for the movement of the core. The rod-like projection 52 passes through a similar bushing 56 in the cap 57 in the upper end of the tube 50. The rod-like projection 52 is provided at its upper end with a head 13 and acts as a riser for operating the piano action, as shown in Figures 2 and 5.

As will be seen from Figures 1, 2 and 5, the note-playing magnets 15 are arranged in rows, each row of magnets being mounted upon an angle bar 50 extending transversely across and parallel to the string frame. The angle bars 50 are insulatably mounted upon the supporting braces 51, the insulation being indicated at 52". A channel bar 53 is insulatably suspended from each angle bar 50 and is lined with insulating material, such as fiber, indicated at 54 A panel 55 of insulating material serves as a cover for this channel bar, which is used as a conduit for the electric cables controlling the individual notes. Terminals 56 are provided on the panels to which are connected one of the terminal leads from each of the noteplaying electromagnets', the control lines for the corresponding notes being connected to the corresponding terminals inside the channel box or conduit 53". The opposite t erininals of the" note-playing electromagnets are directly connected with the anglebars 50, which serve as a common connecting line for all the electromagnets.

The operation of the various circuits controlling the mechanical devices of the piano will be clear from a consideration of Figure 7 In this figure the various parts are shown diagrammatically, the parts and electromagnets corresponding to those hereinbefore described being indicated the same refers ence numerals. Two main connections 60 and 61 are provided for the supply of alternating current for the operation of the instrument. The line 60 is directly connected with the contact roller 61*, over which moves the perforated note sheet 62. Co-operating with'the contact roller 61 and the note sheet- 62 are a plurality of contact members 63' controlling the note magnets 15". contacts controlling the expressiondevices and the volume of soundare provided, as

will be hereinafter described. From each contact 63 a connector 64 leads to a point: of"

connection 56, with which is connected" a terminal line from the corresponding noteplaying magnet 15. The other terminals of the note-playing magnets are all connected" to a common connector or'line 5.0", corresponding to the anglebar 50 previously described. The line50" is connected with a coil 66 which, in turn, is connected-through line 67' with the other current line 61. The switch 84 is opened in playlng-by' means of a perforated roller! It will thus be apparent that when av perforation in sheet 62 corresponding to a given note passes between a contact 63' and contact roll 61, current will pass through that contacttothe corresponding noteplaying magnet 15, the

connector 50, the inductance 66 and the line 67 to the outlet line 61. The fixed inductance of the coil 66 will determine't-he force. with which the core of the note-playing magnetis centered and consequently will determine. the volume of sound of the note. I

For varying the loudness of tone additional means closed'by circuits through the contact roller 6,1 are, provided. For decrease ing the current and for correspondingly dew.

creasing the volume ofsound, a contact 6'8'3i's provided, whlch, when it engages the contact roller 61, closes a shunt circuit through.

the, line, 69 and coil. 70' to. the 1, line 67"; The coil 70' is wound in the same direction Other contact '71 is provided, which, when it engages contact roll 61 through a perforation in the note sheet provided for the purpose, closes a shunt circuit through the line 72 and the coil 73' to the line 67. The coil 73 is wound'in a reverse direction to the coil 66 and consequently when current is passed through coil 73,the inductance is decreased and'th'e current actuating the electromagnets 1 5 energized while the current through contact 71 is closed, is greater than. the normal current? t The'electromagnets- 21 and 23 controlling the hammer-'railare energized by the operation of contacts 74- and 75 respectively. When contact 74 engages the contact roll 61 through a suitable perforation in the note sheet, a circuit is closed through the line 76 to the electromagnet 21 and line 77 leading to the line 78 connecting withthe main 61. A single perforation in the note sheet, causing a momentary energizing of the electromagnet 21 is sufficient, as has been previously explained, since by co-operation ofthe core of electromag'net 23-, the core of magnet 21 is held in position until magnet 23 is energized When contact 7 5 engages I contact roll 61 through a.- perfo'ration in the note sheet, a circuit is" closed through line 7 9 and electromagnet 2,3, which is energized to retract its coreand release the core of its electromagnet 21 in'the' manner previously described. The damper control magnets 21 and 23- are controlled in similar manner from contacts 80' and 81, respectively. The line lead-ing from contact 80 to electromagnet 21 is indicated bynumeral 83 and that leading from contact 81toelectromagnet 2-3- is indicated by numeral 82.

In Figure I circuits arediagrammatically shown for the control of the piano playing devices; from keys and" pedals such as are in use in ordinary pianos. hen itis desired to use the manual and" foot operated controls instead of'the'note-playing keys, the switch 8 1. is closed',.thereby establishing a connection between the line- 50"" and the line 67 depression of the key. Each of ,the' contact springs 87 is directly connected with a common connector 90 leading to a .coil or.

Forciblc depression of the key causes en'- gagement of the base or" the key with the contact spring 88 as well as the contact spring 87. The contacts 88 are each connected with the common connector 92, which connects directly with the line 91 and shunts out of the circuit the inductance 66. When a circuit through one of the contacts 88 and the base of the key is closed, it is thus apparent that the inductance 66 is shunted around witha corresponding increase in cur rent through the electromagnet 15 being energized .and a resulting increased volume of sound. 7 I p g To soften the tone during manual operation, the pedal 93 may be employed. This pedal is connected to the main conductor 61 by a connection 94:. hen the pedal is depressed, itengages a contact 95, closing a circuit through the line96 and coil to 'the line 91. The coil 70 being wound in the same direction as the coil 66, increases the inductance 1n the latter and thereby clecreases the current passing to'the note-play-j ing electromagnet 15 being energized at the moment. The operation of the pedal-93 and'the coil 70 thus corresponds to that of the contact 68 and the coil 70 in operation with the note sheet.

The .pedal 97 controls the energizing of the damper operating magnets 21 and 28 lVith the switch 98 closed, the pedal is connected to the main line 61. Normally, the end of the pedal 97 engages contact 99, thereby closing the circuitthrough the line 100, line 83 and electromagnet 23 ,On depressing pedal 97 circuit through the contact 99 is opened and circuit through the contact 101 is closed. Current then passes through the connecting line 102 and line 82toelectromagnet 21, energizing the latter to raise the dampers 4:6 from the strings. Release of the pedal 97 breaks the circuit through contact 101 and immediatelymakes the circuit through contact 99, thereby immediately energizing the el ectromagnet 23" and releasing the damper.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in View of the prior art. v

lVhat I regard as new, and desire to secure by Letters Patent, is:-

1. In a piano action, 1n combination, a

beingcnergized as does the inductance 66 in operating with the note sheet. 7

movable hammer-rail, means for moving the hammer-rail comprising an operating member normally tending to move in one direction, an velectromagn'et coil, a movable core therein, a rod secured to said core and projecting therefrom, its end resting against the operating member, said core being normally heldout of central position in the magnet coil, means for passing alternating current through the electromagnet coil to thereby bring the core to the center thereof to actuate said operating member and change the position of the hammer-rail, a second electromagnet coil,-a movable core therein, means formoving said core out of position in said second electromagnet coil, means actuated by said core for engaging and latchingthe core of the first-mentioned electromagnet coil when the latter has been moved to central position, and independently controllable means for passing alternating current through the second electromag mentioned armature has served to operate said actuating member, and circuits for said electromagnets, including a tracker bar, and associatedcontacts adapted to be controlled by a music sheet.

3. In a piano action having a 'movable hammer-rail spring-actuated toward the strings, the combination with said rail of means for controllably retracting it, comprising a lever extending from the rail, an electromagnet-coil having a movable core provided with a headed rod on its advanceend into the path of which said lever extends, means for energizing and de-energizing said core, a second electromagnet-coil having a movable core provided with a headed rod adapted to interlockingly engage the first-mentioned headed rod when the first-mentioned coil is energized, means i for projecting said second-mentioned core to efi'ectsaid interlocking engagement, and means for energizing the second-mentioned coil to cause retraction ofthe second-mentioned core and thus ei ect release of the first-mentioned core.

4:. In a piano action, in combination, a movable hammer-rail, a lever adapted to retract said hammer-rail, a spring tending to move the hammer-rail toward the strings,

an electromagnet coil, a movable core there in equipped with a projection having a head resting against said lever, said core being normally held out of position in the magnet coil, means for energizing and deenergizing said magnet coil, a second electromagnet coil, a movable core therein equipped with a projection adapted to interlock with said head, and means for energizing and de-energizing said second-mentioned electromagnet coil.

5. In a piano action, a spring-held member, an electromagnet having an armature operative upon the closing of the electric circuit of said magnet to actuate said mean 1 m-entioned magnet operating upon closure 20 of its electric circuit to retract-its armature and release the first-mentioned armature, and controlling means for the circuits of said electromagnets comprising a tracker bar, associated contacts, and an interposed music sheet.

HENRY K. SANDELL. 

